IB 105 Lecture 7-8

Type I survivorship curve
Survival is high until old age
Type II survivorship curve
Mortality is spread evenly among all age groups
Type III survivorship curve
Very high mortality among the young
2.List the factors that influence population growth rates and population density.
r = b – d

Sex Ratio—Relative number of males and females in a population.
Age Distribution—Number of individuals of each age in the population.Dispersal: Movement of individuals
Emigration: leaving a population, often from crowded areas or in response to environmental change
Immigration: emigrating individuals become immigrants in a new population (joining a population)

Population Density
Number of individuals per unit area.
3.Describe the difference between exponential and logistic growth and why populations don’t grow exponentially forever.
exponential-The number of individuals in each generation is a multiple of the previous generation
Logistic growth describes this “S” shaped growth curve.
4.Tell the four main factors determining carrying capacity.
Raw material availability
Energy availability
Waste accumulation and disposal
Organism interaction
5.Explain why populations cycle.
See lynx hare example in slides
6.Know the key life history traits.
Life history traits – characteristics of an individual that influence survival and reproduction
Age at maturity
Number of offspring produced
Number of reproductive events
1.Describe the past, present, and projected future world population of humans (explain figure on slides 3 & 4).
population has become exponential graph, shot up.
2.List the 6 factors that affect human population growth rate.
Same as for other species:
Birth rate
Death rate
Sex ratio
Age distribution
3.Explain why women have more children in male-dominated societies and fewer children in developed countries.
In male-dominated societies, traditional role of women is to marry & have children
4.List the two factors have the greatest control on birth rates.
1. Cultural role/status of women
2. Desires of women to have children
& access to birth control
5.Recall the current size of the World Population and the US Population.
U.S. 310,825,424
(10 million more than one year ago)
World 6,900,142,775
6.Explain how political policies in China and India changed their population growth rates.
China, 1 child law in 1979

1. Little government intervention until recently
2. Some states emphasizing improving quality of life
Decrease infant mortality
Encourage education for women
3. Others enforcing sterility